User Experience

Picture-in-Picture mode

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Picture-in-picture in Android 8.0.

Android 8.0 (API level 26) allows activities to launch in
picture-in-picture (PIP) mode. PIP is a
special type of multi-window mode
mostly used for video playback. PIP mode was originally available for
Android TV only; Android 8.0 makes the feature available
on other Android devices.

When an activity is in PIP mode, it is in the paused state, but should
continue showing content. For this reason, you should make sure your app
does not pause playback in its onPause()
handler. Instead, you should pause video in onStop(), and resume playback in onStart(). For more information, see
Multi-Window
Lifecycle.

To specify that your activity can use PIP mode, set
android:supportsPictureInPicture to true in the manifest.
(Beginning with Android 8.0, PIP does not require the
android:resizeableActivity manifest attribute.
However, you must set
android:resizeableActivity to `true` if your activity supports other
multi-window modes.)

Android 8.0 (API level 26) introduces a new object, PictureInPictureParams,
which you pass to PIP methods to specify how an activity should behave
when it is in PIP mode. This object specifies properties such as the
activity's preferred aspect ratio.

The existing PIP methods described in
Adding
Picture-in-picture can now be
used on all Android devices, not just on Android TV. In addition,
Android 8.0 provides the following methods to support
PIP mode:

The specified activity is placed in a corner of the screen; the rest of
the screen is filled with the previous activity that was on screen.
The activity entering PIP mode goes into the paused state, but remains
started. If the user taps the PIP activity, the system shows a menu for
the user to interact with; no touch events reach the activity while it is
in the PIP state.

Activity.setPictureInPictureParams():
Updates an activity's PIP configuration settings. If the activity is
currently in PIP mode, the settings are updated; this is useful if
activity's aspect ratio changes. If the activity is not in PIP mode,
these configuration settings are used regardless of the
enterPictureInPictureMode() method that you call.

Notifications

In Android 8.0 (API level 26), we've redesigned notifications to
provide an easier and more consistent way to manage notification behavior
and settings. These changes include:

Users can long-press on app launcher icons to view
notifications in Android 8.0.

Notification channels: Android 8.0 introduces
notification channels that allow you to create a user-customizable channel
for each type of notification you want to display. The user interface refers
to notification channels as notification categories. To learn how
to implement notification channels, see
Managing
notification channels.

Notification dots: Android 8.0 introduces support for displaying
dots, or badges, on app launcher icons. Notification dots reflect the
presence of notifications that the user has not yet dismissed or acted on.
To learn how to work with notification dots, see
Notification
badges.

Snoozing: Users can snooze notifications, which causes them to disappear
for a period of time before reappearing. Notifications reappear with the
same level of importance they first appeared with. Apps can remove or update
a snoozed notification, but updating a snoozed notification does not cause
it to reappear.

Notification timeouts: You can set a timeout when creating a
notification using
setTimeoutAfter().
You can use this method to specify a duration after which a notification
should be canceled. If required, you can cancel a notification before the
specified timeout duration elapses.

Notification settings: You can call
setSettingsText()
to set the text that appears when you create a link to your app's
notification settings from a notification using the
Notification.INTENT_CATEGORY_NOTIFICATION_PREFERENCES intent.
The system may provide the following extras with the intent to filter
the settings your app must display to users: EXTRA_CHANNEL_ID,
NOTIFICATION_TAG, and NOTIFICATION_ID.

Notification dismissal: Users can dismiss notifications themselves, and
apps can remove them programmatically. You can determine when a notification
is dismissed and why it's dismissed by implementing the
onNotificationRemoved() method from the
NotificationListenerService class.

Background colors: You can set and enable a background color for a
notification. You should only use this feature in notifications for
ongoing tasks which are critical for a user to see at a glance. For
example, you could set a background color for notifications related to
driving directions, or a phone call in progress. You can also set the
desired background color using
setColor(). Doing so
allows you to use setColorized() to enable the use of a background color for a notification.

Messaging style: In Android 8.0, notifications that use the
MessagingStyle class display
more content in their collapsed form. You should use the
MessagingStyle class for
notifications that are messaging-related. You can also use the
addHistoricMessage() method to provide context to a conversation by adding
historic messages to messaging-related notifications.

Autofill framework

Account creation, login, and credit card transactions take time and are prone to
errors. Users can easily get frustrated with apps that require these types
of repetitive tasks.

Android 8.0 (API level 26) makes filling out forms, such as login
and credit card forms, easier with the introduction of the Autofill Framework.
Existing and new apps work with Autofill Framework after the user opts in to
autofill.

Fonts in XML

Android 8.0 (API level 26) introduces a new feature, Fonts in XML, which
lets you use fonts as resources. This means, there is no need to bundle fonts
as assets. Fonts are compiled in R file and are automatically
available in the system as a resource. You can then access these fonts with the
help of a new resource type, font.

The Support Library 26 provides full support to this feature on devices
running API versions 14 and higher.

For more information, about using fonts as resources and retrieving system fonts,
see Fonts in XML.

Autosizing TextView

Android 8.0 (API level 26) lets you set the size of your text expand or
contract automatically based on the size of the TextView. This means, it is much
easier to optimize the text size on different screens or with dynamic content.
For more information, about autosizing TextView in Android 8.0,
see Autosizing TextView.

Adaptive icons

Android 8.0 (API level 26) introduces adaptive launcher icons. Adaptive icons support visual
effects, and can display a variety of shapes across different device models. To learn how to
create adaptive icons, see the Adaptive Icons
guide.

Color management

Android developers of imaging apps can now take advantage of new devices
that have a wide-gamut color capable display. To display wide gamut
images, apps will need to enable a flag in their manifest (per activity)
and load bitmaps with an embedded wide color profile (AdobeRGB,
Pro Photo RGB, DCI-P3, etc.).

WebView APIs

Android 8.0 provides several APIs to help you manage
the WebView objects that display web content in your app.
These APIs, which improve your app's stability and security, include the
following:

Maximum screen aspect ratio

First, Android 8.0 introduces the
maxAspectRatio attribute, which you
can use to set your app's maximum aspect ratio. In addition, in Android 8.0 and higher, an app's
default maximum aspect ratio is the native aspect ratio of the device on which the app is running.

Multi-display support

Beginning with Android 8.0 (API level 26), the platform offers enhanced
support for multiple displays. If an activity supports multi-window mode and
is running on a device with multiple displays, users can move the activity
from one display to another. When an app launches an activity, the app
can specify which display the activity should run on.

Note: If an activity supports
multi-window mode, Android 8.0 automatically enables
multi-display support for that activity. You should test your app to make
sure it works adequately in a multi-display environment.

Only one activity at a time can be in the resumed state, even if the
app has multiple displays. The activity with focus is in the resumed state;
all other visible activities are paused, but not stopped. For more information
on the activity lifecycle when several activities are visible,
see Multi-Window
Lifecycle.

When a user moves an activity from one display to another, the system
resizes the activity and issues runtime changes as necessary. Your activity
can handle the configuration change itself, or it can allow the system to
destroy the process containing your activity and recreate it with the new
dimensions. For more information, see
Handling Configuration
Changes.

The adb shell is extended to support multiple displays.
The shell start command can now be used to launch an activity,
and to specify the activity's target display:

adb shell start <activity_name> --display <display_id>

Unified layout margins and padding

Android 8.0 (API level 26) makes it easier for you to specify situations where opposite sides
of a View element use the same margin or padding.
Specifically, you can now use the following attributes in your layout XML
files:

Pointer capture

Some apps, such as games, remote desktop, and virtualization clients, greatly
benefit from getting control over the mouse pointer. Pointer capture is a new
feature in Android 8.0 (API level 26) that provides such control by delivering all mouse events
to a focused view in your app.

Starting in Android 8.0, a View in your app can request
pointer capture and define a listener to process captured pointer events. The
mouse pointer is hidden while in this mode. The view can release pointer capture
when it doesn't need the mouse information anymore. The system can also release
pointer capture when the view loses focus, for example, when the user opens
another app.

For information on how to use this feature in your app, see
Pointer capture.

App categories

Android 8.0 (API level 26) allows each app to declare a category that it fits
into, when relevant. These categories are used to cluster together apps of similar
purpose or function when presenting them to users, such as in Data Usage, Battery Usage, or
Storage Usage. You can define a category for your app by setting the
android:appCategory attribute in your <application>
manifest tag.

Android TV launcher

Android 8.0 (API level 26) includes a new content-centric,
Android TV home screen experience, which is available with
the Android TV emulator and Nexus Player device image for Android 8.0. The new home screen organizes
video content in rows corresponding to channels, which are each populated with programs by an app on
the system. Apps can publish multiple channels, and users can configure which channels that they
wish to see on the home screen. The Android TV home screen also includes a Watch Next row, which is
populated with programs from apps, based on the viewing habits of the user. Apps can also provide
video previews, which are automatically played when a user focuses on a program. The APIs for
populating channels and programs are part of the TvProvider APIs, which are distributed as a Android
Support Library module with Android 8.0.

AnimatorSet

Starting in Android 8.0 (API level 26), the AnimatorSet API now supports seeking and playing in
reverse. Seeking lets you set the position of the animation set to a specific
point in time. Playing in reverse is useful if your app includes animations
for actions that can be undone. Instead of defining two separate animation
sets, you can play the same one in reverse.

Input and navigation

Keyboard navigation clusters

If an activity in your app uses a complex view hierarchy, such as the one in
Figure 2, consider organizing groups of UI elements into clusters for easier
keyboard navigation among them. Users can press Meta+Tab, or Search+Tab on
Chromebook devices, to navigate from one cluster to another. Good examples of
clusters include: side panels, navigation bars, main content areas, and elements
that could contain many child elements.

Note: Clusters cannot be nested, although non-nested
clusters may appear at different levels of the hierarchy. If you attempt to
nest clusters, the framework treats only the top-most
ViewGroup element as a cluster.

On devices that have touchscreens, you can set a cluster-designated
ViewGroup object's
android:touchscreenBlocksFocus element to true to
allow cluster-only navigation into and out of that cluster. If you apply this
configuration to a cluster, users cannot use the Tab key or arrow keys to
navigate into or out of the cluster; they must press the cluster navigation
keyboard combination instead.

View default focus

In Android 8.0 (API level 26), you can assign the View that should
receive focus after a (re)created activity is resumed and the user presses a
keyboard navigation key, such as the tab key. To apply this "focused by default"
setting, set a View element's
android:focusedByDefault attribute to true in the
layout XML file containing the UI element, or pass in true to
setFocusedByDefault() in your
app's UI logic.

Speech output

Activities and services can use instances of
TextToSpeech to dictate and pronounce content. As of
Android 8.0 (API level 26), your app can obtain more precise timing information
about when a text-to-speech engine begins speaking individual synthesized words,
as long as the engine provides this information. You can use this functionality
to call attention to specific words as the text-to-speech engine speaks
them.

To use these text-to-speech engine improvements in your app, register an
instance of UtteranceProgressListener. As part of the
registration process, include a handler for the
onRangeStart()
method.

The text-to-speech engine calls
rangeStart() to record
the point in time at which it expects audio playback of a specific range of text
to start. When the audio for that text range starts playback, your app's
onRangeStart()
method executes. Your app can then respond to this callback, such as by
highlighting the text range that's associated with the utterance.

For more information about tracking the playback progress of a text-to-speech
engine, see the UtteranceProgressListener class
reference.

Cached data

Android 8.0 (API level 26) gives better guidance and behaviors around cached data. Each
app is now given a disk space quota for cached data, as returned by
getCacheQuotaBytes(UUID).

When the system needs to free up disk space, it will start by deleting cached files from apps
that are the most over their allocated quota. Thus, if you keep your cached data under your
allocated quota, your cached files will be some of the last on the system to be cleared when
necessary. When the system is deciding what cached files to delete inside your app, it will
consider the oldest files first (as determined by modified time).

There are also two new behaviors that you can enable on a per-directory basis to control
how the system frees up your cached data:

StorageManager.setCacheBehaviorAtomic() can be used to indicate
that a directory and all of its contents should be deleted as a single atomic unit.

Finally, when you need to allocate disk space for large files, consider using the new
allocateBytes(FileDescriptor, long) API, which will automatically clear
cached files belonging to other apps (as needed) to meet your request. When deciding if the
device has enough disk space to hold your new data, call
getAllocatableBytes(UUID) instead of using
getUsableSpace(), since the former will consider any cached
data that the system is willing to clear on your behalf.

Content provider paging

We've updated content providers to include support for loading a large
dataset one page at a time. For example, a photo app with many thousands of
images can query for a subset of the data to present in a page. Each page
of results returned by a content provider is represented by a single Cursor
object. Both a client and a provider must implement paging to make use of
this feature.

Content refresh requests

The ContentProvider and
ContentResolver classes now each include a
refresh() method, making it easier for clients to know whether
the information they request is up-to-date.

You can add custom content refreshing logic by extending
ContentProvider. Make sure that you override the
refresh() method to return
true, indicating to your provider's clients that you've attempted
to refresh the data yourself.

Your client app can explicitly request refreshed content by calling a
different method, also called
refresh(). When calling this
method, pass in the URI of the data to refresh.

Note: Because you may be requesting data over a network,
you should invoke refresh() from
the client side only when there's a strong indication that the content is stale.
The most common reason to perform this type of content refresh is in response to
a swipe-to-refresh
gesture, explicitly requesting the current UI to display up-to-date content.

JobScheduler improvements

Android 8.0 (API level 26) introduces a number of improvements to JobScheduler. These improvements make it easier for your app
to comply with the new background
execution limits, since you can generally use scheduled jobs to replace
the now-restricted background services or implicit broadcast receivers.

You can now associate a work queue with a scheduled job. To add a work item to
a job's queue, call
JobScheduler.enqueue().
When the job is running, it can take pending work off the queue and process it.
This functionality handles many of the use cases that previously would have
called for starting a background service, particulary services that implement
IntentService.

You can now call
JobInfo.Builder.setClipData()
to associate a ClipData with a job. This option enables
you to associate URI permission grants with a job, similarly to how these
permissions can be propogated to Context.startService(). You can also use URI permission grants with intents
on work queues.

Custom data store

Android 8.0 (API level 26) lets you provide a custom data store to your preferences, which can
be useful if your app stores the preferences in a cloud or local database, or
if the preferences are device-specific. For more information about
implementing the data store, refer to
Custom Data Store.

VolumeShaper

Audio focus enhancements

Audio apps share the audio output on a device by requesting and abandoning audio focus.
An app handles changes in focus by starting or stopping playback, or ducking its volume.
There is a new AudioFocusRequest class. Using this class as the parameter of
requestAudioFocus(),
apps have new capabilites when handling changes in audio focus:
automatic ducking and
delayed focus gain.

Media metrics

A new getMetrics() method returns a PersistableBundle
object containing configuration
and performance information, expressed as a map of attributes and values.
The getMetrics() method is defined for these media classes:

Kotlin

Java

The MediaMuxer
can now handle any number of audio and video streams. You are no longer limited
to one audio track and/or one video track. Use addTrack()
to mix as many tracks as you like.

The MediaMuxer can also add one or more metadata tracks containing user-defined per-frame
information. The format of the metadata is defined by your application. The
metadata track is only supported for MP4 containers.

Metadata can be useful for offline processing. For example, gyro signals from
the sensor could be used to perform video stabilization.

When adding a metadata track, the track's mime format must start with the prefix
"application/". Writing metadata is the same as writing video/audio data except
that the data does not come from a MediaCodec. Instead, the app passes a
ByteBuffer with an associated timestamp to the
writeSampleData() method.
The timestamp must be in the same time base as the video and audio tracks.

The generated MP4 file uses the TextMetaDataSampleEntry defined in section
12.3.3.2 of the ISOBMFF to signal the metadata's mime format. When using MediaExtractor to extract the file with metadata track, the mime
format of the metadata will be extracted into MediaFormat.

However, accessing large media files from a remote data source introduces some
challenges:

Media players require seekable access to a file from a documents provider.
In cases where a large media file resides on a remote data source, the
documents provider must fetch all of the data in advance and create a snapshot
file descriptor. The media player cannot play the file without the file
descriptor, thus playback cannot begin until the documents provider finishes
downloading the file.

Media collection managers, such as photo apps, must traverse a series of
access URIs to reach media that's stored on an external SD card via scoped
folders. This access pattern makes mass operations on media—such as
moving, copying, and deleting—quite slow.

Media collection managers cannot determine a document's location given its
URI. This makes it difficult for these types of apps to allow users to choose
where to save a media file.

Android 8.0 addresses each of these challenges by improving the Storage Access
Framework.

Custom document providers

Starting in Android 8.0, the Storage Access Framework allows
custom documents
providers to create seekable file descriptors for files residing in a
remote data source. The SAF can open a file to get a native seekable file
descriptor. The SAF then delivers discrete bytes requests to the documents
provider. This feature allows a documents provider to return the exact range
of bytes that a media player app has requested instead of caching the entire
file in advance.

Direct document access

As of Android 8.0 (API level 26), you can use the
getDocumentUri() method to
get a URI that references the same document as the given mediaUri.
However, because the returned URI is backed by a
DocumentsProvider, media collection managers can access
the document directly, without having to traverse trees of scoped directories.
As a result, the media managers can perform file operations on the document
significantly more quickly.

Caution: The getDocumentUri() method only locates media files; it doesn't grant apps
permission to access those files. To learn more about how to obtain access
permission to media files, see the reference documentation.

Paths to documents

When using the Storage Access Framework in Android 8.0 (API level 26), you can use the
findDocumentPath() method, available in both
the DocumentsContract and
DocumentsProvider
classes, to determine the path from the root of a file system given a document's
ID. The method returns this path in a
DocumentsContract.Path object. In cases where a file
system has multiple defined paths to the same document, the method returns the
path that is used most often to reach the document with the given ID.

This functionality is particularly useful in the following scenarios:

Your app uses a "save as" dialog that displays the location of a
particular document.

Your app shows folders in a search results view and must load the child
documents that are within a particular folder if the user selects that
folder.

Note: If your app has permission to access only some of the documents
in the path, the return value of findDocumentPath() includes only
the folders and documents that your app can access.

Connectivity

Wi-Fi Aware

Android 8.0 (API level 26) adds support for Wi-Fi Aware, which is based on the Neighbor
Awareness Networking (NAN) specification. On devices with the appropriate
Wi-Fi Aware hardware, apps and nearby devices can discover and communicate
over Wi-Fi without an Internet access point. We're working with our hardware
partners to bring Wi-Fi Aware technology to devices as soon as possible. For
information on how to integrate Wi-Fi Aware into your app, see Wi-Fi Aware.

Bluetooth

Android 8.0 (API level 26) enriches the platform's Bluetooth support by adding the following
features:

Support for the AVRCP 1.4 standard, which enables song-library browsing.

Support for the Bluetooth Low-Energy (BLE) 5.0 standard.

Integration of the Sony LDAC codec into the Bluetooth stack.

Companion device pairing

Android 8.0 (API level 26) provides APIs that allow you to customize the
pairing request dialog when trying to pair with companion devices over
Bluetooth, BLE, and Wi-Fi. For more information, see
Companion Device
Pairing.

Sharing

Smart sharing

Android 8.0 (API level 26) learns about users' personalized sharing
preferences and better understands for each type of content which are the right
apps to share with. For example, if a user takes a photo of a receipt, Android
8.0 can suggest an expense-tracking app; if the user takes a selfie, a social media
app can better handle the image. Android 8.0 automatically learns all these
patterns according to users' personalized preferences.

Smart sharing works for types of content other than image, such as
audio, video, text, URL,
etc.

To enable Smart sharing, add an ArrayList of up to three
string annotations to the intent that shares the content. The annotations should
describe the major components or topics in the content. The following code example
shows how to add annotations to the intent:

Text classifier

On compatible devices, apps can use a new Text Classifier to check whether a
string matches a known classifier entity type and get suggested selection
alternatives. Entities recognized by the system include addresses, URLs,
telephone numbers, and email addresses. For more information, see
TextClassifier.

Accessibility

Android 8.0 (API level 26) supports several new accessibility features for
developers who create their own accessibility services:

Security & Privacy

Permissions

The ANSWER_PHONE_CALLS permission allows your app to answer
incoming phone calls programmatically. To handle an incoming phone call in
your app, you can use the
acceptRingingCall()
method.

The READ_PHONE_NUMBERS permission grants your app read access to
the phone numbers stored in a device.

These permission are both classified as
dangerous
and are both part of the
PHONE
permission group.

New account access and discovery APIs

Android 8.0 (API level 26) introduces several improvements to how
apps get access to user accounts. For the accounts that they manage,
authenticators can use their own policy to decide whether to hide accounts from,
or reveal accounts to, an app. The Android system tracks applications which can
access a particular account.

Testing

Instrumentation testing

Run against non-default app processes

You can now specify that a particular instrumentation test should run against
a process outside your app's default process. This configuration is useful if
your app contains multiple activities that run in different processes.

To define non-default process instrumentation, navigate to your manifest
file, then to the desired
<instrumentation> element. Add the
android:targetProcess attribute, and set its value to one of
the following:

The name of a particular process.

A comma-separated list of process names.

A wildcard ("*"), which allows the instrumentation to run
against any launched process that executes code in the package specified in
the android:targetPackage attribute.

While your instrumentation test is executing, you can check which process
it's testing by calling getProcessName().

Report results during a test

You can now report results while your instrumentation test is executing,
rather than afterward, by calling addResults().

Mock intents for tests

To make it easier to create isolated, independent UI tests for your app's
activities, Android 8.0 (API level 26) introduces the
onStartActivity() method. You override this method in a custom subclass of the
Instrumentation.ActivityMonitor class to handle a particular
intent that your test class invokes.

When your test class invokes the intent, the method returns a stub
Instrumentation.ActivityResult object instead of executing
the intent itself. By using this mock intent logic in your tests, you can focus
on how your activity prepares and handles the intent that you pass to a
different activity or to an entirely different app.

Runtime & Tools

Platform optimizations

Android 8.0 (API level 26) brings runtime and other optimizations to the platform that
result in a number of performance improvements.
These optimizations include concurrent-compaction garbage collection,
more efficient use of memory, and code locality.

These optimizations result in faster boot times, as well as better performance in both the
OS and apps.

Updated ICU4J Android Framework APIs

Android 8.0 (API level 26) extends the
ICU4J Android Framework
APIs—which is a subset of the ICU4J APIs—for app developers to
use under the android.icu package. These APIs use localization data
present on the device, so you can reduce your APK footprint by not compiling the
ICU4J libraries in your APK.